The case of a massive pelvis chondroma in a 15-year-old male is described. The patient was previously treated operatively due to multiple chondro-osseous exostoses. An extensive chondrous tumour was detected in the patient's pelvis and abdomen during a follow-up visit. This was accompanied by symptoms of intestinal obstruction and impaired micturition. CT scans showed an extensive tumour filling the entire minor pelvic cavity and proximal femur with impression and infiltration of the femoral blood vessels, and displacement of both ureters, colon and urinary bladder causing urinary retention. The tumour caused severe disturbances of anatomical relations leading to dysfunction of the urinary and gastrointestinal systems. After appropriate preparation, the patient underwent surgery by a multidisciplinary team comprising an orthopaedic surgeon, a general surgeon and a urologist. After laparotomy and exposure of the retroperitoneal space, a giant (about 3.5 dm3) chondro-osseous tumour was resected. After 5 weeks another operation was made and another tumour, greater than an adult man's fist, was removed from the medial aspect of the right hip. The postoperative course was uncomplicated, the patient felt immediate relief as regards the urinary and gastrointestinal disturbances. His locomotion became noticeably better. A histological examination confirmed the preliminary diagnoses of a chondroma and a chondro-osseous lesion. Outpatient follow-up and additional work-up (ultrasound, CT) showed resolution of urine retention with an appropriate urinary bladder position and tumour-free minor pelvis cavity and proximal femur.